LyX ⇒ Math delimiters showing nonsense symbols

[feon2]

Hi. I've been using Lyx since 2017, and I found it to be a very good tool. I recently formatted my notebook and installed the newest lyx version. It works fine, like always, but there is a weird bug in the math delimiter: it's not showing the actual delimiters, but random symbols. How could I fix that? I did a quick web search and I did not find anything related to that problem.

Thanks!

(delimiter image)